Stroke is a major public health problem in the United States (US), with an estimated 800,000 strokes each year and an estimated 7 million stroke survivors. Cognitive decline and impairment are major contributors to disability after a stroke, ranging from mild cognitive impairment with minor impact on daily activities to severe dementia that requires substantial assistance including nursing home placement. Alzheimer's disease (AD) is a fatal form of dementia and is the fifth leading cause of death among people aged ?65 years in the US. Stroke and AD are strongly age-dependent. Because the US population is aging, the population at risk for these conditions will increase over the coming decades. There is increasing evidence of associations between stroke and AD/dementia. It is estimated that over 60% of patients have cognitive impairment within the first year after their stroke, and the prevalence is even higher after a recurrent stroke. The risk of developing dementia among stroke survivors is two to four times that of the general age-matched population. It is estimated that 10-15% of stroke patients have dementia prior to their stroke, but there are limited data on stroke outcomes for patients with AD. African-American and Hispanic populations are at increased risk for both conditions, but little is known about the outcomes for individuals with both diseases. This administrative supplement will build upon the Disparities in Patterns of Recurrent Stroke in the Elderly parent R01 grant to examine the interrelationship between AD and ischemic stroke in elderly Medicare beneficiaries and assess potential disparities by demographic characteristics and geographic location. Medicare administrative data will be used to achieve the following specific aims: 1) among elderly fee-for-service beneficiaries hospitalized with ischemic stroke, determine patterns in the rate of AD within 1 year and assess the impact of AD on stroke recurrence, post- acute care services, and cost; and 2) among beneficiaries with an AD diagnosis, determine patterns in the rate of stroke within 1 year and assess the impact of the event on outcomes. The proposed study will address research priorities identified by the National Institute on Aging, the Institute of Medicine, and the National Institute of Neurological Disorders and Stroke, to develop surveillance systems to understand the continuum of disease prevention, progression, treatment, and outcomes, particularly for vulnerable populations. The project also addresses priorities in Healthy People 2020, to reduce the morbidity and costs associated with, and maintain or enhance the quality of life for, persons with dementia, including AD. Clinical practice, public policy, and reimbursement decisions are increasingly informed by administrative datasets. Results from this supplement will provide much needed information on the outcomes, resource utilization, and costs for individuals who develop both stroke and AD. Anticipating the future needs of our aging population is critical to inform decisions about the allocation of adequate and equitable health care across the nation, particularly for high-risk and vulnerable populations.